In my init I've specified this:
You can change these to ALWAYS and NO. More restrictive world parameter settings override these. ALWAYS lets you see the features in the Local view during embark, and NO stops you from looking for features in the site finder (though if you really want to stop the finder, it might be better for you to generate worlds that restrict the use of this feature completely, in which case you don't need to change the settings here).
[SHOW_EMBARK_RIVER:ALWAYS]
[SHOW_EMBARK_POOL:ALWAYS]
[SHOW_EMBARK_M_PIPE:ALWAYS]
[SHOW_EMBARK_M_POOL:ALWAYS]
[SHOW_EMBARK_CHASM:ALWAYS] ###
[SHOW_EMBARK_PIT:ALWAYS] O (well symbol)
[SHOW_EMBARK_OTHER:ALWAYS]
[SHOW_EMBARK_TUNNEL:ALWAYS] ==== (smoothed wall symbol)
And while I've seen some extra symbols appear in the local map, I'm not sure what they mean. Does anyone have a key for each of these features??
I've now seen blue ~ and double ~, and red ones, too, as well as #, and the pound symbol. But what is what?
I've embarked on a few of these locations and tried tunneling in to find these features but I haven't been able to verify any of them, except lines of # being underground chasms (only verified because one breached the surface and I could see it all from the beginning).
Cheers.
EDIT: Got three, the tunnel, pit and chasm. Added them to the cut n paste above. I'm hypothesising that the light blue pound symbol is the "Other" which I'm also guessing is HFS.